Sensory Contributions to Skilled Performance Chapter 3

Objectives Explain the contributions and limitations of a closed-loop model of movement control Understand the various ways that sensory information is used in movement control Discuss the various roles of vision in movement control Understand how sensory contributions to movements are part of a conceptual model of motor performance

Preview How is a rugby player able to watch the ball leave a teammate’s hand with a few tenths of a second of viewing time and realize she must turn her back on the ball and cut sharply in one direction to catch it? She predicts the ball’s flight correctly, visually focuses on it, times the ball’s arrival into her hands, and compensates for other external factors by grasping the ball with two hands. (continued)

Preview (continued) How is so much accomplished in such a short time? How are corrections made during skilled performance?

Overview Processing vast amounts of information quickly and accurately and making effective adjustments as needed Processes that allow performers to detect patterns of information in the environment and use the information to predict future actions The neuromuscular system, the conceptual model of motor performance, and principles of visual control as they relate to movement

Exteroception From the environment Outside of the body Highly visual

Proprioception Information that comes from within the body, largely from the muscles and joints

Interoception: From Inside the Body Kinesthesis—Sensory information coming from the motor system that signals contractions and limb movements Vestibular apparatus—located in inner ear; information about balance, posture, and orientation Muscle spindle—located in skeletal muscle; sends information about muscle length to CNS (continued)

Interoception: From Inside the Body (continued) Golgi tendon organs—located between muscle and tendon; provide information about force in the muscles Cutaneous receptors—located in the skin; detect pressure, temperature, and contact

Closed-Loop Control System Involves the use of feedback and error detection and correction processes to maintain the desired goal Used to control slow and deliberate movements (continued)

Closed-Loop Control System (continued) Good for detecting slow movement Not good for explaining rapid movement Does not account for discrete tasks (continued)

Closed-Loop Control System (continued) Comparator—error detection Executive—brain; determines actions to take to reach goal Effector—carries out decisions Feedback—provides information on current state

Open-Loop Control Response selection and response programming require considerable time and attention. In the closed-loop conceptual model, corrections occur a few hundred milliseconds after an error occurs. The error signal is processed in the stimulus-identification stage. (continued)

Open-Loop Control (continued) A movement correction is chosen in the response-selection stage. Modifications to the movement are organized and initiated in the response-programming stage.

Compensations for Muscle Movements M1—monosynaptic Most rapid, unconscious, one synapse, little environmental impact, inflexible M2—polysynaptic Longer muscle, adjusts more than M1, higher-level function, knee-jerk, sensory, can’t modify once begun (continued)

Compensations for Muscle Movements (continued) Triggered reaction Wineglass effect, learned, conscious, cutaneous receptors M3—voluntary reaction time Voluntary; affected by instruction, anticipation, and stimulus responses; supported by Hick’s law

Visual Systems Focal—Identifies objects in center of visual field; is conscious and affected by light Ambient—Detects orientation of body in environment; is nonconscious and peripheral

Optical Flow Detects movement of patterns of light from the environment Perceives motion, positions, timing, stability, velocity, and direction

Vision How does vision affect balance? Visual dominance—visual information dominates information coming from the other senses Visual capture—visual information attracts a person’s attention more easily than other forms of information